This invention relates generally to a process and apparatus for the disposal of biological waste which includes, but is not limited to, medical waste, infectious waste, pathological waste, animal waste, and sanitary waste and henceforth referred to as biological waste.
The cost of disposing of biological waste in the U.S. is more than $5 billion per year. The capital cost of the equipment required is in the hundreds of millions of dollars. All institutions and businesses that generate and handle this category of waste have needs to provide safe effective and inexpensive disposal of the waste. In recent years there has been increasing concern over the disposal of biological waste. The two principal methodologies for the disposal of this waste are incineration and dumping in landfills.
The Environmental Protection Agency (EPA) has issued new regulations that require incinerators to reduce their emissions to very stringent levels for products that are exhausted from biological waste incinerators. The new regulations will, for practical purposes, close down or require major modifications to almost all such incinerators by the year 2001. Municipal landfills have already begun to refuse to accept biological waste especially if it is identifiable as medical waste. Most alternatives to these two methods involve thermal methods that emit products into the atmosphere that are not acceptable.
Biological waste is defined as any waste that is considered by any of, but not limited to, the following statutes and regulations:
New Jersey State Statute, xe2x80x9cComprehensive Regulatory Medical Waste Management Actxe2x80x9d, P.L. 1989, c. 34 (C.13.1E-48.13).
New York State Environmental Conservation Law, TITLE 15, xe2x80x9cSTORAGE, TREATMENT, DISPOSAL AND TRANSPORTATION OF REGULATED MEDICAL WASTExe2x80x9d, Section 27-1501. Definitions.
New York State Public Health Law, TITLE XIII, xe2x80x9cSTORAGE, TREATMENT AND DISPOSAL OF REGULATED MEDICAL WASTExe2x80x9d, Section 1389-aa. Definitions.
CALIFORNIA HEALTH AND SAFETY CODE, SECTION 117635. xe2x80x9cBiohazardous Waste xe2x80x9d Title 25 Health Services, Part I.
Texas Department of Health, Chapter 1 Texas Board of Health, xe2x80x9cDefinition, Treatment, and Disposition of Special Waste from Health Care-Related Facilities, Section 1.132 Definitions.
40 C.F.R. 60.51(c) PROTECTION OF ENVIRONMENT; Standards of performance for new stationary sources.
40 C.F.R. 240.101 PROTECTION OF ENVIRONMENT; Guidelines for the thermal processing of solid wastes (Section P only).
49 C.F.R. 173.134 TRANSPORTATION; Class 6, Division 6.2-Definitions, exceptions and packing group assignments.
33 C.F.R. 151.05 TITLE 33-xe2x80x9cNAVIGATION AND NAVIGABLE WATERS; VESSELS CARRYING OIL, NOXIOUS LIQUID SUBSTANCES, GARBAGE, MUNICIPAL OR COMMERCIAL WASTE, AND BALLAST WATERxe2x80x9d;
Definitions (medical waste only).
Biological waste is a relatively new problem for today""s technological society. The definition of this waste has been expanding in its coverage of materials that must be handled in a controlled manner. The foregoing list of state statutes and United States federal regulations are overlapping but necessary to accurately define the materials because no single statute or regulation covers all the materials to which this invention applies.
Mediated Electrochemical Oxidation (MEO) processes represent a mature science in the industrial complex over the past two decades. The orientation to date has been focused on the dissolution of transuranic metals and destruction of organics in mixed waste from the chemical reprocessing of irradiated nuclear reactor fuel, and controlled oxidation and destruction of organic-based military munitions and organophosphorus chemical weapon nerve agents, as is represented by patents dating back into the mid-eighties.
Research into the application of the MEO process to date has involved the use of the process to dispose of materials in these areas. In the first area, the MEO uses an electrochemical cell in which the electrolyte is generally restricted to a composition of nitric acid and silver ions. The silver ion serves as the regenerable mediating oxidizing species which is used in a oxidative dissolution of plutonium dioxide to recover plutonium contained in solid waste from processes, technological and laboratory waste (U.S. Pat. No. 4,749,519), and subsequently extended to the dissolution of the plutonium dioxide component of mixed oxide fuel (coprecipitated uranium and plutonium oxide) (U.S. Pat. No. 5,745,835).
In the second area, the MEO process was used: (a) for the decomposition (i.e. oxidation) of organic matter contained in the mixed solid waste generated in extracting plutonium from irradiated nuclear reactor fuel (U.S. Pat. Nos. 4,874,485; 4,925,643); (b) controlled oxidation of organic military munitions (U.S. Pat. No. 5,810,995); and (c) destruction of organophosphorus nerve agents (U.S. Pat. No. 5,855,763).
Both of the two areas discussed have involved similar use of the MEO process using nitric acid and silver ions being generated by an electrochemical cell with the anode and cathode being separated by a membrane. The two uses have differed in the temperature range used in each of the applications. The second use is operated between 50xc2x0 C. and slightly below 100xc2x0 C. to take advantage of the generation of the secondary oxidation species to assist in oxidizing organic materials. The first use is operated below 50xc2x0 C. (generally around 25xc2x0 C. or room temperature) to minimize Ag(II)xe2x80x94water reactions because unlike the Ag(II) ion, not all of the secondary oxidizing species have an oxidation potential sufficient to oxidize plutonium dioxide to a soluble species.
Others have substituted cerium and nitric acid, cobalt and nitric acid, and cobalt and sulfuric acid for the silver and nitric acid as the electrolyte (U.S. Pat. Nos. 5,516,972; 5,756,874). The temperatures vary among the three electrolytes being substituted for the silver and nitric acid combination. Most recently, ruthenium in a nearly neutral solution has been proposed as the electrolyte in a MEO process to decompose organic materials, which would operate between 50xc2x0 C. and 90xc2x0 C. (Platinum Review, Jul. 1998). All of the descriptions reviewed are similar in their application to the decomposition of organic materials and differ in their choice of electrolyte(s), pH, concentrations, and the operating temperature range over which they are applied.
These and other objects and features of the invention are apparent in the disclosure, which includes the above and ongoing written specification, with the drawings.
The invention relates to a method and apparatus for the mediated electrochemical oxidation (MEO) of wastes, such as biological materials and has particular application to, but is not limited to, biological waste, medical waste, infectious waste, pathological waste, animal waste, and sanitary waste (henceforth collectively referred to as biological waste).
A mediated electrochemical oxidation process involves an oxidizing electrolyte, wherein at least one oxidizing species is electrochemically generated in an electrochemical cell. A membrane in th e electrochemical cell separates the anolyte and catholyte. The preferred MEO process uses as mediator ions, for example, the following metals: Ag, Ce, Co, Fe, Mn or Ru in nitric acid, sulfuric acid or phosphoric acid as the anolyte. A cost reduction can be achieved in the a basic MEO process by using anions that are useable in alkaline solutions such as NaOH and KOH, since the oxidation potentials usually decrease with increasing pH. The catholyte may contain the same acid as the anolyte, but not necessarily in the same concentration. The process operates over the temperature range from room temperature up to a temperature slightly below the boiling point of the electrolyte solution (usually the temperature will be below 100xc2x0 C.) during the destruction of the biological waste.
The MEO process begins with the electrochemical oxidation of the dissolved mediator ions to one of their higher valence states, after which these ions oxidize the biological waste and are themselves reduced down to their initial lower valence state, whereupon they are again electrochemically oxidized back up to their higher valence state. In the case of some higher valence oxidized species, a second oxidation process is possible.
At higher temperatures (i.e., above about 50xc2x0 C.) these higher valence oxidizer species react with the aqueous solution to produce a variety of powerful oxidizing free radicals (e.g., .OH, etc.) and hydrogen peroxide, etc. Decomposition of the hydrogen peroxide into free hydroxyl radicals is well known to be promoted by ultraviolet irradiation. The MEO process biological waste destruction rate using these species, therefore, will be increased by ultraviolet irradiation of the reaction chamber anolyte.
The principals of the oxidation process in which the hydroxyl free radical cleaves chemical bonds and oxidizes organic compounds have been widely documented, resulting in the formation of successively smaller chained hydrocarbon compounds. The intermediate compounds formed are easily oxidized to carbon dioxide and water during sequential reactions.
One distinction between the prior art and this invention is in the application to biological waste, which distinctly differs from all prior applications. The prior art processes and their supporting patents may focus on organic materials, but they clearly distinguish from biological waste both in describing their processes and specifically in the examples of materials being treated by their processes. The materials are generally characterized as complex organic molecules associated with industrial processes. The prior art does not describe or refer to a single process that is biological in nature. Prior art processes that specifically deal with biological waste do not use the MEO process to dispose of those categories of waste.